In recent years, the use of a digital still camera (in the following, referred to as DSC) allowing a user to check a captured image immediately has been expanding rapidly. As a lens barrel for this DSC, a so-called collapsible lens barrel, which can be made shorter when not in use, generally is adopted in view of its portability when not in use.
FIG. 35 is an exploded perspective view showing a conventional collapsible lens barrel (see JP 2002-107598 A, for example). This collapsible lens barrel 60 is an optical system in which a single cam barrel 61 moves moving lens frames 62 and 63 back and forth so as to change a focal length. The inner peripheral surface of this cam barrel 61 is provided with cam grooves 64 and 65, which determine moving paths of the moving lens frames 62 and 63, respectively. Three cam pins 62a provided on the outer peripheral surface of the moving lens frame 62 and three cam pins 63a provided on the outer peripheral surface of the moving lens frame 63 mate with the cam grooves 64 and 65, respectively, whereby the moving lens frames 62 and 63 move in an optical axis (Z-axis) direction. The cam barrel 61 is provided outside a fixed barrel 70 and can rotate freely around the optical axis. An outer periphery of the cam barrel 61 is provided with a gear 66, which engages with a driving force transmitting gear 67. The driving force transmitting gear 67 is connected to an output axis of a cam barrel driving actuator 69 via a reduction gear train 68. Thus, when the cam barrel driving actuator 69 is driven, the driving force is transmitted via the reduction gear train 68 to the driving force transmitting gear 67, thereby rotating the cam barrel 61. This moves the moving lens frames 62 and 63 along respective shapes of the cam grooves 64 and 65, so that zooming is carried out from a collapsed state via a wide angle end.
FIG. 36 is a development showing the cam grooves 64 and 65 formed on the inner peripheral surface of the cam barrel 61. As shown in FIG. 36, the cam grooves 64 and 65 are formed in a circumferential direction of the cam barrel 61 so as to extend from a collapsed position through a wide angle end position to a telephoto end position. Accordingly, when the power of DSC is turned on, the moving lens frames 62 and 63 shift from the collapsed position to the wide angle end position, which is the next stop position, and stop there for an image capturing.
Further, with an increase in the optical zooming factor, the influence of camera shake has become conspicuous. In order to reduce this influence, a DSC including an image blurring correcting device is on its way to becoming commercialized. As this image blurring correcting device for DSC, there has been a suggested method of moving a correcting lens group in two directions that are perpendicular to the optical axis so as to correct the camera shake by a user, thereby obtaining a stable image (see JP 2001-117129 A, for example).
However, in the conventional collapsible lens barrel described above, since the reduction gear train 68 and the cam frame (cam barrel 61) are used for zooming, there have been problems in that an increase in a zoom speed and a reduction in a zoom noise are difficult to achieve.